During many types of chemical reactions in a liquid medium, a gas reaction product may be formed, for example: carbon dioxide (CO2) through chemical reactions such as decarboxylation in a Claisen condensation; and nitrogen in the Sandmeyer reaction of diazo compounds or in the Balz-Schiemann reaction, in the production of arylfluorures, or in reactions of isocyanates and thioisocyanates.
Various methods have been proposed for separating and removing gas from the liquid such as, for example:
a) a method of degassing with a separating film or membrane described, for example, in U.S. Pat. No. 6,342,092, U.S. 2009/090215 A1, U.S. 2009/208790 A1, U.S. 2009/0162864 A1, U.S. 2009/0143251 or allowing selective passage of either the gas or the liquid;
b) a degassing method using an adsorbent having an absorption capacity for the gas or the liquid, see for example EP 1080771, U.S. 2006/0,249,020;
c) a method of degassing by decompression, see, e.g., WO 2008/155 175, EP 2089131, U.S. 2009/0159537, U.S. 2009/0145167;
d) a method of degassing by heating, for example see TW 2006/19586;
e) a method of degassing by mechanical or inertial methods such as centrifugal separators or by utilizing a cyclone, for example, WO 2007/94727; WO 2009/929022; U.S. 2009/0242481, EP 1068990, U.S. Pat. No. 6,036,749, U.S. Pat. No. 5,976,227, U.S. Pat. No. 3,849,095, U.S. 2009/0100811, U.S. 2009/0050121; and
f) a trapping method, for example EP 2024052, U.S. Pat. No. 6,830,735.
In EP 1527804 and U.S. 2009/090215 A1, the separation of a byproduct gas is carried out continuously in an outer pipe having a portion with a larger section. The device for gas-liquid separation is installed between the units of a multi-step or multi-unit process, in an intermediate section of straight pipe having sufficient length to complete the immediately previous reaction, and which conveys the liquid reaction mixture from the second unit from the first mixing unit while continuously removing gas by-product generated by immediately previous reaction (see FIG. 2 of this document).
In WO 2009/054176, any inert gases and uncondensed vapors are continuously discharged from a condenser through openings made in a central channel, see FIG. 3.
U.S. Pat. No. 7,604,781 B2 discloses microcircuit reaction apparatus capable of separating liquid and gas phases and a method of using the apparatus in which the reactant stream passes through a separation zone 510 that widens before encountering a coalescing element 508 formed for example by fibers or foam (column 11, lines 6-10 of this document). This separation zone, which may contain a separation plate 515 (column 11, lines 9-11), is positioned at the end of the apparatus, before the exit, which constitutes a different technical solution than that of the invention described herein below.
U.S. 2009/0,282,978 discloses a separator for microfluidic multi-phase separations based on membranes, see in particular FIG. 3.
U.S. Pat. No. 6,637,463 discloses a microfluidic circuit comprising a plurality of microfluidic flow channels which are subdivided, see FIGS. 1-8. This circuit includes a microfluidic structure for separating gas bubbles from a liquid, comprising an extraction chamber in fluid communication with a drainage chamber, the fluid traveling through the extraction chamber to the drainage chamber in a first direction with a system of upper tanks and lower tanks necessitating a complicated design and manufacturing process.